It’s more like “in a world where every group of n horses are the same colour”, no matter of whether that world is the real world or not, “prove that any group o

It’s more like “in a world where every group of n horses are the same colour”, no matter of whether that world is the real world or not, “prove that any group of n+1 horses are the same colour”. This inductive step proves nothing about the real world, it needs a base case to kick things off. If you can prove it true for n=5 say, then the inductive step gives you every higher number.